Collapsible wheel-chair

Abstract

A wheel-chair has a foldable frame structure (10) which is lockable in the unfolded state and carries wheels (11, 12) and a back (13). In the folded state, all fixed parts are folded up between the wheels of the wheel-chair. The frame structure (10) is box-shaped and has foldable set and bottom members (15, 17) and foldable front and rear wall members (19, 20). These seat, bottom, front and rear wall members are pivotally connected to side wall members (14). The seat and bottom members (15, 17) consist of two parts and are folding upwards and are mechanically interconneted by means of a central wall (18) for common folding movements. The front and rear wall members (19, 20) also consist of two parts and are mechanically interconnected for common folding movements by means of a rod (22) disposed underneath the bottom portion (17). The back (13) is also made of two parts (26, 27) which are pivotally connected to the rear edge of a respective part (15) of the seat member and extend downwardly towards the bottom member (17) such that they can be locked in the unfolded state by means of a locking device (37) provided on the rigid member (22). The front and rear wall members (19, 20) are angled rearwards in all positions of the wheel-chair. The large wheels (11) of the wheel-chair have a driving ring (89) which can be moved between an inner and an outer position and which is fixed on the hub (60) of the wheel by means of leaf springs (90) and which, when the driving ring is moved between said inner and outer positions, passes an unstable position of maximum tension of the leaf springs. Also, the large wheels (11) of the wheel-chair are provided with disc brakes (80) the brake discs of which are connected to the frame structure (10) of the wheel-chair by means of a rotation-inhibiting pin member (87) and by means of a nut and screw thread (81, 83) which, when a brake handle (86) is pivoted, will move the brake disc (80) into frictional engagement with a braking surface (67) on the side face of the hub (60) of the wheel.

We claim: 
     
       1. A collapsible wheel-chair having a foldable frame structure (10) which can be locked in the unfolded state and which supports the wheels (11, 12) and the back (13) of the wheel-chair and which comprises a box-shaped seat having side wall members (14) connected to foldable seat and bottom members (15, 16; 17) and to foldable front and rear wall members (19; 20), characterized in that the seat and bottom members (15, 16; 17) are foldable upwards and each consist each of two rigid, hingedly interconnected seat and bottom portions, respectively, (15, 16; 17) and are mechanically interconnected for common folding movements, that the front and rear wall members (19; 20) are foldable rearwards and each consist of two rigid, hingedly interconnected front and rear wall portions, respectively, (19; 20) and are mechanically interconnected by means of a rigid member (22) extending underneath the bottom portion (17), and that the back (13) can be raised and consists of two back portions (26, 27) which are pivotally connected to the rear edge of a respective part (15) of the foldable seat member (15, 16) and which in the unfolded state of the wheel-chair extend downwards behind the rear wall member (20) for releasably engaging a locking device (37) provided on the frame structure. 
     
     
       2. Wheel-chair as claimed in claim 1, characterized in that the wheels (11, 12) of the wheel-chair are connected to corner pieces (53, 71) which are each disposed at the corner of a respective side wall member (14) and connected to hinge pins (30, 31, 32) for the rear wall, front wall and bottom portions (20, 19, 17). 
     
     
       3. Wheel-chair as claimed in claim 1 characterized in that the front and rear wall members (19, 20) have a length exceeding the width of the frame structure in the unfolded state and that the two front wall portions (19) and also the two rear wall portions (20) in the unfolded state of the frame structure are directed obliquely rearwardly and make an obtuse angle with each other. 
     
     
       4. Wheel-chair as claimed in claim 1, characterized in that the two back portions (26, 27) of the back (13) are adapted to abut on the rear wall (20) with their parts extending downwardly behind the rear wall member and prevent folding of the rear wall when the back is in its raised position. 
     
     
       5. Wheel-chair as claimed in claim 1, characterized in that those parts of the two back portions (26, 27) which are located below the pivotal connection (28, 47) of the back portions with the rear edge of the corresponding seat member (15) are obliquely cut (at 50) in a downward direction away from each other in order, during the inital phase of an upward folding movement of the seat and bottom members (15, 16; 17), to make it possible, in the plane of the back, to move apart the parts of the back portions located above said pivotal connection (28, 47), and that the mutually facing edges of the two back portions above said pivotal connection have engagement means (43-46, 48, 49) which in the fully unfolded state of the frame structure engage with each other in order to prevent any relative movement of the back portions (26, 27) at right angles to the planes thereof. 
     
     
       6. Wheel-chair as claimed in claim 5, characterized in that the engagement means (43-46, 48, 49) consist of complementary flanges (43, 45, 48) and recesses (44, 46, 49) in the mutually facing edge portions of the two back portions (26, 27). 
     
     
       7. Wheel-chair as claimed in claim 1, characterized in that the locking device (37) for the back (13) is provided on a rearwardly extending part of the rigid member (22) disposed underneath the bottom member (17). 
     
     
       8. Wheel-chair as claimed in claim 7, characterized in that the locking device (37) is fixedly mounted on the rigid member (22) and that each back portion (26, 27) has a locking projection (38) which in the fully unfolded state of the frame structure is in locking engagement with the locking device (37) and prevents lowering of the back and which, when the parts of the back portions (26, 27) located above the seat member are moved apart in the plane of the back, is moved out of said locking engagement to permit folding the back. 
     
     
       9. Wheel-chair as claimed in claim 1, characterized in that the two seat portions (15, 16) of the seat member are hingedly interconnected by means of a hinge shaft (34) extending through a central recess (36) on the seat member (15, 16) to serve as a handle (35) for lifting the wheel-chair for folding and transporting it. 
     
     
       10. Wheel-chair as claimed in claim 1, characterized in that the rigid member (22) provided underneath the bottom portion (17) has an attachment (23) for or is connected to a footrest (24, 41, 42). 
     
     
       11. Wheel-chair as claimed in claim 1, characterized in that the wheel-chair has two large wheels (11) and at least one small wheel (12), the small wheel or wheels (12) being designed in a per se known manner as castors and the large wheels (11) being disposed at such a distance from the frame structure (10) that there is sufficient space for the back portions (26, 27) between them and the frame structure when the wheel-chair is in the folded state. 
     
     
       12. Wheel-chair as claimed in claim 11, characterized in that each of the large wheels (11) of the wheel-chair has a driving ring (89) which can be moved between an inner and an outer position. 
     
     
       13. Wheel-chair as claimed in claim 12, characterized in that the driving ring (89) of each wheel (11) is connected to the hub (60) of the wheel by means of at least three leaf springs (90) which are provided substantially in the plane of the wheel and which in their untensioned state have a length which is greater than the difference between the diameter of the hub and the diameter of the driving ring and which are maintained constantly tensioned in a gently S-shaped state by means of a flexible connection (91) between the wheel (11) and the driving ring (89) and which have such a length and such an S-shape that when the driving ring (89) is pressed inwards towards the wheel (11), they pass an unstable position of maximum tension and thereafter urge the driving ring (89) against the wheel (11). 
     
     
       14. Wheel-chair as claimed in claim 1 characterized in that it has a brake disc (80) which is connected to the frame structure (10) and which, by means of a brake handle (86), can be brought into engagement with the side face of the associated wheel hub (60) for braking the wheel (11). 
     
     
       15. Wheel-chair as claimed in claim 14, characterized in that the brake disc (80) is connected to a nut (81) which in turn is connected to the brake handle (86) and is in threaded engagement with a threaded journal (83) fixed on the frame structure (10).